Field of the Invention
The present invention relates to a liquid treatment apparatus and a liquid treatment method that performs a predetermined chemical liquid treatment to a substrate by supplying a heated treatment liquid to the substrate while rotating the substrate.
Description of Related Art
In semiconductor device manufacturing process, a resist film having a predetermined pattern is formed on a treatment target film formed on a substrate, e.g., a semiconductor wafer (hereinafter referred to simply as “wafer”), a treatment such as etching, ion implantation or the like is performed to the substrate using the resist film as a mask. After the treatment, the resist film which is no longer necessary is removed from the wafer.
Recently, a SPM treatment is often used for removing the resist film. The SPM treatment is performed by supplying the resist film with a SPM (sulfuric acid hydrogen peroxide mixture) of a high temperature obtained by mixing sulfuric acid and hydrogen peroxide solution.
An example of a resist removing apparatus for performing the SPM treatment is disclosed in Japanese patent laid-open publication JP2007-35866A (Patent Document 1). The apparatus of Patent Document 1 includes a spin chuck that holds and rotates a wafer, a splash guard (also called “treatment cup”) that surrounds the wafer held by the spin chuck, and a nozzle that supplies a surface of the wafer, on which the resist is formed, with the SPM. The high-temperature SPM supplied onto the surface of the wafer reacts with the resist to produce fume. The fume is gas or mist originated from the SPM and the resist. The fume widely spreads within a chamber of the resist removing apparatus, which may cause generation of contaminant for the wafer. In order to avoid such spreading of the fume, the apparatus of Patent Document 1 is provided with a circular shield plate (also called “top plate”) that covers the upper end opening of the splash guard and the wafer held by the spin chuck from above.
The SPM treatment processes a wafer with a high-temperature SPM. The wafer draws the heat from the SPM, so that the temperature of the SPM is likely to lower at locations remote from the discharging point of the SPM. In addition, the peripheral portion of the wafer tends to be cooled due to rotation of wafer. Thus, uneven temperature distribution within a surface of the wafer is likely to occur, and thus the treatment result is likely to be non-uniform. The nozzle of Patent Document 1 supplies SPM to the center of the wafer. Thus, it may be considered that the SPM temperature at the peripheral portion of the wafer is likely to lower. However, Patent Document 1 does not recite any countermeasure against this problem.
Japanese patent laid-open publication JP2008-4878A (Patent Document 2) discloses a resist removing apparatus, which includes a plate (vacuum spin chuck) that holds a back surface (no resist is formed thereon) of the wafer by suction and rotates, a SPM nozzle that supplies SPM to a front surface (having resist and directed upward) of the wafer held by the plate, and a mixed fluid nozzle that supplies a mixed fluid of SPM and nitrogen gas to the front surface of the wafer held by the plate. A heater, which is capable of heating the whole area of the wafer, is embedded within the plate. The wafer is heated by the heater from the back surface of the wafer such that the temperature of the front surface of the wafer becomes within a range from about 200 to 250° C. In this state, the mixed fluid of SPM and nitrogen gas is sprayed to the substrate from the mixed fluid nozzle with the nozzle is moving (scanning), so that the resist is removed. Disposing a heater in the rotation plate as in Patent Document 2 will result in a complicated structure of the rotation plate. In addition, the heater may possibly be exposed to the chemical liquid since the chemical liquid contacts with the plate.